Circuit breaker with magnetic arc extinguishing means



G. w. PETERS 2,411,892

CIRCUIT BREAKER WITH MAGNETIC ARC EXTINGUISHING MEANS Dec. 3, 1946.

3 Sheets-Sheet 2 Filed July 8, 1943 m .m m. m u m M 4. www

Dec. 3, 1946. G. w. PETERS 2,411,892

CIRCUIT BREAKER WITH MAGNETIC ARC EXTINGUISHING MEANS Filed July 8, 1945 3 Sheets-Sheet 3 1464/5276 MAGNET/c Marie/71. Marge/m 57 M146 IVE 7' /C M19 Tile/19A,

INVEN TOR.

or electron discharge Aistic is which comprises an intensely brilliant core survthe usual provisions flaming gases.

Patented Dec. 3, 1946 cmcurr g 2,411,892 BREAKER wrru MAGNETIC Anc Ex'rmGmsmNG MEANS Gerhard W. Peters, Akron, Ohio Aprucauon July 8,1943, serial No. 493,841 12 claims. (ci. zoo- 141) My invention relates to means and methods for controlling an electric arc or electron discharge between electrodes or contacts .in an electrical circuit, and more particularly to such means and methods for extinguishing an arc or electron discharge between electrodes or contacts of a circuit breaker or current interrupter.A

Upon the establishment of an uncontrolled arc between two electrodes or contacts in an electricalcircuit, the charactersuch that it suddenly grows into a full arc rounded by a cooler region of flaming gases. The arc occurs with explosive suddenness and the accompanying flame which is one of the arc phenomena may, in many instances, propagate itself to great length and cross-sectional area compared with the arc core proper. Consequently, the flame itself must be ruptured as well as the arc discharge to interrupt the circuit.

In the prior art circuit breakers, attempts have been made to house or confine the flame by walls or barriers to -prevent injury to adjacent parts and to prevent the flame parts and making a short circuit in the contacter. The flame therefore must be dealt with concurrently with the arc proper.

fil

from bridging metal My invention utilizes the reaction between the field of the arc or electron discharge extending from one electrode to the other and a magnetic eld to control the arc structure in a new and novel manner, `and is applicable to any device where it is found desirable or necessary to control the current flowing between spaced electrodes or to rupture the current flowing between spaced electrodes such as found in circuit breakers, contactors and other interruptors of electrical current.

My invention makes a radical departure from all the prior art devices and principles embodied therein, by utilizing a magnetic field of such strength and pattern as to modify the structure of the arc and to substantially keep it from growing beyond control. The evolution of flame is prevented; the explosive sound usually accompanying the rupturing of flaming arcs is absent;

for dealing with the destructive and dangerous flame are unnecessary; and

` the burning of the contacts is greatly reduced and their life accordingly prolonged.

The strength and the pattern of my magnetic field is such as to modify the arc and give it the appearance of a flow with substantially no The resistance of the arc may be varied without materially stretching it by chang- ,exert the necessary to resist the ends ing the strength of the magnetic field and complete control is maintained over 'the structure of the arc to keep it from growing. My device may be characterized as an inhibitor of ionization which prevents the arc from growing rather than a de-ionizer which allows the arc to grow to a full arc after which de-ionization occurs to extinguish the arc and the resultant flame.

It is accordingly among the objects of my invention:

To provide generally an improved means and method utilizing a magnetic eld for confining the arc or electron discharge between the contacts or.

electrodes;

To provide for establishing a strong magnetic field to influence the arc or electron discharge between the interrupting electrodes and to inhibit ionization which keeps the discharge from STOWDS;

To provide for controlling the structure of the arc by a strong magnetic field;

To modify the arc and give it substantially the appearance of a glow with no flaming gases;

To provide for increasing the resistance of the arc without materially increasing the length thereof;

To provide means to control a discharge or arc from the moment it begins to form so as to resist the growth of the discharge and simultaneously forces to extinguish said discharge; i

To provide for causing each end of the electron discharge which exists between two electrodes to be forced to remain substantially on the surface of the interrupting electrodes by employing a magnetic field of such strength and pattern as of the discharge from leaving the contacts, and for causing the discharge to be constrained substantially within Vthe volume of space embraced between the electrodes;

To provide for directing the magnetic flux in a funnel-like fashion through one electrode, the space between the electrodes and the other electrode;

' To provide for focusing the magnetic flux so that it will pass through the discharge space between the electrodes in a funnelf-like fashion, in such a position that the axis of the contacts is substantially parallel with the axis of the funnellike flux pattern, or that both axes substantially coincide with each other;

To direct fiux in a funnel-like fashion with one of the electrodes positioned at. the throat of the funnel-like flux lines and with the other electrode positioned within the rim of the funnellike circuit;

l iux lines, wherein a discharge which exists between the electrodes is magnetically restrained substantially within the boundary of the funnellike ux lines;

To provide forcausing each end of the discharge which exists between two electrodds to be A forced toward the central portions of the electrodes;

To provide and utilize a magnetic eld, that directs the flux of suicient strength in the discharge space between the electrodes at an angle thereacross, whereby the angularly directed ux has strong vertical and horizontal components of ux which react with the ux produced by the discharge itself to immediately extinguish the discharge without the necessity of removing the discharge from the space between the interrupting electrodes;

To provide a means and Lmethod for extinguishing a discharge drawn between the contacts or electrodes, which progressively transversely constricts the discharge inwardly from all sides toward the central axis of the discharge.

To providea combination of discharge enclosing chamber, means for producing a magnetic ux in a funnel-like pattern inside the discharge enclosing chamber, and means for drawing a discharge between two electrodes inside the chamber A and within the limits of the funnel-like ux pattern, wherein the discharge which exists -between the electrodes is substantially kept from contacting side wall portions of the chamber;

To provide in the arc chamber a recess having an insulating surface disposed transversely of a path between the stationary contact and the opening in which the movable contact moves.

To provide for keeping the arc onthe contacts away from the recess and prevent deposits created by the arc from lodging upon the insulating surface in'the recess and establishing a con.- ductive path between the stationary contact and the opening in which the movable contact moves.

To provide for utilizing the magnetic material of part of the magnetic circuit as a cooling enclosing chamber for the discharge; I

To providev for substantially enclosing the electrodes between which a discharge is drawn in an enclosing chamber and for directing a magnetic ux of a funnel-shaped pattern across the discharge space betwenvthe electrodes;

To provide for substantially enclosing the electrodes between which a discharge is drawn in a shell-like metal housing, whereby the shell-like metal housing constitutes part of the magnetic To provide for electrically insulating one of the magnetic pole means of the magnetic circuit from the electric circuit, when construction is such that both poles may come into contact with the discharge. Y Y

Other objects and a fuller understanding of my invention may be had by referring to the following description andv claims, taken in conjunction with the accompanying drawings, in which: p Y

Figure 1 isa longitudinal sectional view of a structure embodying my invention;

Figure 2 is a cross-sectional view taken from the line 2-2 of Figure 1, with parts beyond the. section plane omitted;

Figure 3 is an enlarged view of the magnetic with the iiux produced by the discharge to inimediately extinguish the discharge;

Figure 4 is a cross-sectional viewgpf a double-V break type of circuit interrupter or contactor embodying the features of my invention;

Figure 5 is a fragmentary view of Figure e showing a modied form of the magnetic circuit;

Figure 6 is a view of a further modied form of the outer shell par't of the magnetic circuit;

Figure '7 is a view similar in general to Figure l but illustrating a modification of the magnetic circuit;

Figure 8 is a cross-sectional view taken from the plane 8 8 of Figure 7, with parts beyond the section plane omitted;

Figures 9 and 10 are views illustrating modications in the central core'construction of my invention; and

Figures 11 and 12 are views similar in general to Figure 1, but illustrating modications utiliz-4 ing permanent magnets instead of the electromagnets for producing a strong magnetic eld.

With reference to Figure l of the drawings, I illustrate'a circuit interrupting device having a pair of interruptingelectrodes 20 and 2i for interrupting the current iiowingk through the load which is energized from the supply conductors il and I8. The reference character 2li represents the stationary electrode and the reference character 2| representsA the movable electrode which may be actuated by any suitable actuating mechanism such as designated by the reference character i9. To improve the interrupting property of the electrodes, each may be provided with contact tips or members which may be made of silver or of any other arc resisting material. The

contact tip for the stationary electrode 20 is desigranged post 24 carried by a suitable insulated block or panel 26. The lower end of the post 24, as shown in the drawings, is provided with a reduced end provided with threads to which the stationaryelectrode 2c maybe threadably con,- nected.. While I have illustrated the stationary I electrode 2li as being threadably connected to the post 24, it is to be understood that my invention contemplates the securing lof the stationary electrode 2B in relative position to the post 2d by any other suitable means. The lower end of the post I 24 where it meets with the threads isiprovided |50 with a shoulder 21. A lock washer 25 may be interposed between the shoulder 21' and the *stationary electrode 20 to rmly secure the stationary electrode 20 upon the post 24.

The upper end of the post 24, as shown 1in Figure 1 of the drawings, is provided with an in-4 tegral stud extension 28 which passes through an opening in the insulated block or panel 26.' The' lower side of the insulated block or panel 26 may be somewhat recessed to receive a circular metal plate 29. The integral stuclextension 28 passes Vthrough an opening Within 'the circular metal plate 29. The diameter of the integral stud extension 28 is smaller than provide a shoulder 34 that rests against'thecircular metal nlate 29, so that when the nut @a the post proper tokwhich threadably engages the upper end oi' the stud extension 28 is ilrmly turned down, the post eldhaving a funnel-like pattern is very` eil'ective 24 is rigidly connected to the insulated block or panel 28. To the uppermost end of the stud extension 28 is attached a terminal clip 33 which may be electrically connected to the supply conductor The terminal clip 33 may be secured to the'stud extension 28 byy means of the nuts 3| and '32. 1

Mounted upon the underneath side of the insulated block or panel 26 is an insulated housing 38 which may be secured to the insulated block or panel 26 by any suitable means. The insulated housing 38 is provided with a' deep cylindrical recess 3`| to receive a cylindrical tubular body 38 having an annular head 39 provided with an opening 40 through which the movable electrode 2| moves.- The upper annular end oi' the tubular body 38 registers with the peripheral edge of the circular metal plate 29. The insulated housing 36 is provided with an opening 4| which is slightly smaller in diameter than the opening 40 in the annular head 39 so that the opening 4| may constitute a. guide for the'movable electrode 2| as it is moved relative to the stationary electrode 20 by the actuating mechanism I9. By means of this construction, the movable electrode 2| does not make electrical contact with the annular head 39 of the tubular body 38, as the electrode is.

moved in and out of the opening 40.

The tubular bocw 38 having the annular head 39 and the circular metal plate 29 constitute a shell-like metal housing for the interrupting electrodes 28 and 2| and the side clearance between the movable electrode 2| and the opening 4| is relatively small to make a relatively tight arcor electron discharge enclosure chamber. 'I'he post 24, the circular metal plate 29, the'tubular body 38 having the annular head 39, constitute a magnetic circuit in which the post 24 comprises one pole portion and in which the annular head 39 constitutes the other pole portion. The lines 43 in Figure 3 illustrate generally the direction of the lines of ux which pass between the two pole portions. The separation of the movable electrode 2| from the stationary electrode20 occurs in the air gap between these two magnetic pole portions' whereby a discharge between the separating electrodes is controlled by the ilux passing between the two pole portions. The flux for the magnetic in interrupting the discharge between the interrupting electrodes. In contro-distinction with prior art devices. my invention appears to inhibit the reproduction of ions which prevents the arc from growing into a full arc with aming gases.

In all of the tests which have been made upon ,f -my invention with a. standing discharge main-f or with substantially no eld at all the discharge appears to have the characteristic of a full are with flaming gases, and since the arc is uncontrolled it generally is inclined to loop or bulge outwardly to oneV side of the spaced contacts, stretching itself to a length many times the distance between the spaced contacts and going through many queer twisting and bending movements of -an indescribable nature. As the magnetic eld is strengthened by increasing the excitation of the magnetizing coil 42, the standing arc goes through a state of conversion and approaches the appearance of a glow discharge with substantially no flaming gases while at the same time decreasing in length and drawing inwardly toward the center of the volume of space between the contacts. AAs the arc is drawn inwardly, it appears to stillen up by the controlled action of the increased ux, causing the bulging and looping characteristics of the uncontrolled arc to disappear. As the magnetic eld is further increased, the arc moves or is drawn further inwardly toward the central portion of the contacts and the glow-like appearancebecomes darker and the arc finally disappears.

The last thing that one can observe upon the disappearance of the discharge is a glow at one I end of the discharge which is apparently the circuit may be set up by means of a magnetizing coil 42 which surrounds the post 24 and which may be energized by the supply conducto-rs l1 and I8. In my invention I provide a strong flux field which controls the structure of the discharge.

. The ux which is established by the magnetizing coil 42 and which ilows between the two pole portions may be characterized as funnel-shaped or fountain-shaped and passes at an angle across the space between the stationary electrode 20 and the movable electrode 2| and cuts the electron discharge which extends between the electrodes at an angle to immediately interrupt the discharge. The axis of the funnel-like flux pattern is preferably made substantially'parallelwith the axis of 'the electrodes. Both axes may substantially coincide with each other. The flux pattern has a strong vertical component of flux and a strong horizontal o-r radial component of ilux which react with the ilux produced by the discharge to control the structure of the discharge. The flux density is the greatest toward the outthe heavy lines in Figure 3.

I have discovered that a strong magnetic ilux cathode glow. Prior to the disappearance of the cathode glow, one can observe a glow at the other end of the discharge which is apparently the anode glow. A dark column appears to exist between the cathode glow and the anode glow. With a strong-magnetic field, the standing -arc when observed by the eyes of an observer gives the appearance of a cone or of the frustum of a cone as explained in my co-pending application. Serial No. 493,848', led July 8, 1943. The base, of the cone or of the frustum of the cone is on the stationary electrode 20., The apex of the cone points toward the movable electrode 2|. VThe sides of the frustum 0f the cone lean inwardly with the cut-off end of the frustum terminating at the movable electrode 2 I. The cone-shaped discharge appears when the supply conductor I1 is positive and when the supply conductor I8 is negative, and the frustum of the cone-shaped discharge appears when the polarity of the conductors is reversed. High speed pictures when shown at low speed or at standstill, reveal that the glow discharge is in the form of a line or an element of the cone or of the frustum of the cone which is whirled or spun around by the magnetic iield, thus appearing to the eyes, because of the speed of rotation, as a cone or a frustum of a cone. With the coneshaped arc, the end of the arc line which clingsto or contacts the movable electrode 2| remains substantially in one place upon the surface of the movable electrode and usually in the central region thereof with the other end lof the arc line which contacts the stationary electrode swinging 'side of the funnel-like pattern, as illustrated by or whirling around in substantially a circle spaced inwardly at a distance from the peripheral edge of the stationary electrode. With the frustum of a sistance of the arc cone-shaped arc. one end of the arc discharge line spins or-whirls around the peripheral edge of the stationary electrode with the other end spinning around the movable electrodev 2i at a distance spaced inwardly from the peripheral edge thereof. A

The frustrum of the cone-shaped arc sometimes approaches the 'shape of a cylinder with both ends of the arc spinning or whirling around the peripheral edges of the electrodes. Sometimes the discharge line or arc which is whirled or spunaround takes the form of a spiral, but ordinarily the spiral is caused to straighten out in which case the arc extends substantially in -a straight line between the separated electrodes. Accordingly; with a strong magnetic eld, the

ends of the discharge line are constrained to re main substantially on the surface of the electrodes and the discharge line itself is forced to remain substantially within the volume of space embraced between the separated electrodes. Sometimes the discharge or arc line, under the condition when a frustum of a cone or a cylinder is formed, may bulge or spiral outwardly a little with its ends clinging upon the electrodes or upon the side edge of the electrodes. In this application the expression substantially within thevolumc of space embraced by the separated electrodes? includes an increased volume of space which may have a diameter substantially twenty (20%) percent greater than the diameter of the electrodes.

sistance of the arc to decrease as'the length of the arc is decreased, yet in my invention the reverse is true in that as the length of the arc ls decreased by the application of a strong magneticfeld, the resistance is increased. The reline or vdischarge when it passes 'from 'one of the spaced contacts to the other in substantially a straight line, as it does in the case of the cone or the frustum of a' cone,

I is more than the resistance of a long or looping Y uncontrolled arc under the action of a Weak field.

Accordingly, the ow of the load current may be varied with a standing arc by changing the magnetic field strength. The increase in resistance appears to resultfrom the fact that as the magnetic eld is increased, the .cross-sectional area of the arc line becomes smaller, decreasing to a relatively thin line arc or discharge. That is to say, the cross-sectional area of the discharge line is-restricted from all sides inwardly toward the -axis of the discharge line and the resistance can bemade so vhigh that the potential across the separated electrodes cannot maintain the flow of current therethrough. As the discharge line appreaches the point of extinguishment, the whirling or spinning of the line substantially dies downv and sometimes appears to remain substantially stationary just prior to its disappearance.l The extinguishment of the discharge is not accompanied by a sudden explosiveness as usually accompanies the rupture of a flaming arc. The evolution of theJ ame is prevented and the burning of the contacts is greatly reduced.

In actual circuit breaker operation, the contacts separate very rapidly and the design and the size of the parts are such that the arc is immediately extinguished upon the rapid opening of the contacts. A person viewing the formation and interruption of the arc under rapidly separating contacts observes only a foreshortened arc, which gives the impression that the foreshortened arc is substantially extinguished berated. With my invention it is not necessary tol provide any special features in the actuating mechanism le to cause the movable electrode tc be separated from the stationary electrode more rapidly than in the make-and-break contactors .of common practice, nor is it necessary to separate theelectrodes a greater distancethan is found in common practice, to eiect interruption of the arc while the electrodes are moving apart.

The tubular body 38 shields the discharge between the two electrodes in such a manner that magnetic disturbances outside the enclosing chamber will not affect the discharge and cause it' to move oi the interrupting electrodes. In addition, any movement of air outside the metal enclosing chamber will not come in contact with the discharge and cause it to move out of the space between the interrupting electrodes. The air which displaces the moving electrode 2l will ilow into the space between the separating electrodes approximately equal from all sides of the electrodes, thus tending to centralize the discharge toward the center of the space between the electrodes. Inasmuch as the clearance between the opening dl and the movable electrode 2| is relatively small the enclosing chamber acts as a pressure chamber which aids in extinguishing the electron discharge. The pressure within the chamber is relatively equal in all directions from the discharge and accordingly there is substantially no unbalanced pressures which would tend to move the ends of the discharge oi the electrodes and from the volume of space between the electrodes.

In Figure 4 I lillustrate a cross-sectional view of a double-break type of circuit breaker or contactor embodying the features of my invention, and corresponding parts are represented by the same reference characters as those found in Figure l. In Figure 4 the movable electrodes 2| are connected together by a bridging member 4l and are simultaneously actuated by the actuating mechanism !9 for interrupting the circuit between the supply conductors I1 and I8. The magnetizing coils in Figure 4 are energized by the load current and bear the reference character 44,. As illustrated, the lower ends of the magnetizing coils .44 are connected to the electrodes 20 by means of clips 45 which are interposed between the electrodes 20 and the lock washers 25. The insulated block or pane1 26 and the insulated housing 36 are suitably connected together and are in turn suitably mounted upon a bracket 4B which may be employed to fasten the double-break type of contacter upon a. suitable stationary support. The upper annular ends of the tubular body 38 areelectrically insulated from the circular metal plates 29 by means of a sheet of insulating material 46 which is disposed between the insulated block or panel 26 and the insulated housing 36. One purpose of the sheet of insulating material 46 is to electrically insulate the annular head 39 of the tubular body 38 from the post 24 and the electrode 26. With the annular head 39 so insulated, all

netic eld does not strike/upon the annular head f 1|)y 33 as the movable electrode 2| is moved away from the stationary electrode 20. As a matter of clearly avoiding all possible tendency for the or arc to discharge or arc to strike upon the annular head 39, I have electrically insulated it from the post 24 and the stationary electrodes 20 in Figure 4. The insulating material 46 is positioned on the top of an annular recess formed by the external surface of the post 24 and theinternal sur-face of the tubular body or shell 38. The open end of the recess is deiined between the external surface of the contact and the internal surface of the tubular body 38 and is in communication with the space surrounding the contacts in the vicinity of the arc. The external surface of the stationary contact 20 and the. post 24 may be designated as a rst portion of the recess, the insulating material 46 asa second portion and the internal surface .of the tubular body 38 as a third portion, and these named comprise a series of surfaces extending from the stationary contact 2|) to the opening in the chamber in which the movable contact operates. The open end of the annular recess is dened by the first and third portions, and the insulating material is between the iirst and third portions. The iiux substantially keeps the arc on the contacts away from the open end of the recess and protects the second portion or insulating material 46 in the recess from the arc to prevent deposits created by the arc Afrom entering the recess and lodging upon the insulating material and establishing a. conductive path between the rst and third portions. The insulating material 46 may be described as an endless insulating surface transversely disposed of a path extending between the stationary contact and the opening in which the movable contact oper-V ates. In other words, the insulating material constitutes a break in any path extending between the stationary contact and the opening in which the movable contact operates. The ilux keeps the arc from entering the recess and effectively sub-divides the recess portion of the cham'- ber from the remaining portion of the chamber between the contacts where the arc occurs.

The openings 4| in the insulating housing 36 and the openings in the annular head 33 respectively define small chambers into which the arc may be drawn by the movable contacts 2| if not immediately extinguished upon the opening of the contacts. The downward movement of the movable contacts in the openings 4| is arrested when the bridging member 41 engages an adjustable stop I9. In my invention, I preferably arrest the movement of the movable contacts in the openings 4|, so that the small chambers will be formed above the movable contacts. The operation of the double-break type of contactor as shown in Figure 4 is substantially the same as that described for Figure 1. As shown in the drawings7 the posts 24 project from the end wall or panel 26 into the recesses to a point whereby the contacts separate in a region which is closer to the opposite end wall of the recesses containing the small chambers Ior openings 4| portions in the order' l0 than to the end wall 23 constituting the top closure end for the annular recesses. inasmuch as the contacts separate in a region relatively close to the small chambers orV openings, the

actuating means may quickly withdraw the movable contacts thereinto, whereby the arc is readily extinguished. In the prior art devices of the doubleebreak type, it has been customary to enclose both sets of interrupting electrodes into one chamber. In my invention in Figure 4, I enclose each set of interrupting electrodes in individual metal chambers so that the electrical discharge from one set of interrupting electrodes rwill not disturb the other set of interrupting` electrodes.

In Figure 5 Ishow a fragmentary view of Figure 4 and illustrate a modification of the magnetic circuit, in that the tubular body 38 in Figure i has been replaced by a fore-shortened tubular body 5| having the annular head 33. An insulated tube 52 is interposed between the upper annular end of the fore-shortened tubular body l'5| andthe insulated block or panel 26. In addition, thecircular metal plate 29 is dispensed with and the shoulder 34 on the post 24 rests against a washer 53. nular head 39 in Figure 5 is substantially the same as that shown in Figure 4 and the path of the iiux between the'post 24 and the annular head 39 is substantially funnel-shaped as hereinbefore described. The insulated tube 52 constitutes an endless insulating surface transversely disposed of a path extending between the stationary contact and the opening in which the movable contact moves and functions substantially the same as the insulating material 46 in Figure 4 to prevent a conductive path from being formed between the stationary contact and the opening in which the movable contact operates.

The flux between the upper annular end of the 'fore-shortened tubular post 5| and the upper endf of the post 24 must pass through non-magnetic material instead of metal as shown invFigure 4. One purpose of showing the invention in the form as illustrated in Figure 5 is to bring out the fact that the electron` discharge or arc between,

the interrupting electrodes may be extinguished evenvthough the magnetic circuit has a high reluctance, since the field strength may be still maintained at a strong value by increasing the ampere turns of the magnetizing coil 44. Hence, the operation of my invention as shown in the form of Figure 5, is substantially the same as that shown in Figure 4. I also iind from testsl that the annular head 39 may be removed, leaving the lowermost annular end of the tubular body 38 as a pole portion through which the ilux passes. The removal of the annular head 39 reduces the eiliciency of the magnetic circuit and the brim of the funnel-like ilux path is broadened or enlarged. The reduction inthe efiiciency of the magnetic circuit may be offset by increasing the ampere-turns of the magnetizing coil 44.

In Figure 6 I show a further modiiied form of the tubular body 38 in that one side of the tube is slotted along the line 54 which has the property of reducing the flow of eddy currents therein. Otherwise, the 'operation of my invention with the slit tubular body 38 is substantially the same as that with no slit. The annular head 39 and the tubular body 38 may be cut into a number of .segments and still come within the purview of my invention. l

In Figures 'land 8 I-illustrate another form of The position of the any asti',

anchoring the annular head 39 thereto. For simplicity, the Figures 7 and 8 do not illustrate the insulated housing 36. The operation of the device as shown in Figures 7 and 8 is substantially the same as that described hereinbeore.

In Figure 9 I show a modication of the stationary electrode which comprises a hollow tube d@ having a clip E59 attached to .the upper end thereof. The hollow 'electrode is electrically insulated from the circular metal plate 2t by means of an insulating washer positioned between the shoulder t2 and the insulated lblccl or panel 2d. The hollow electrode d@ may .be secured to the insulated block or panel 25 by means of a nut Sd. .As illustrated, a plug di made of magnetic material is positioned inside ofthe hollow electrode d@ and may loe anchored therein by any suitable means. rlhe plug di in combination with the tubular body 38, and the circular metal plate 3@ constitutes the magnetic circuit. n In Egure l Il show a modication of the arrangement shown in Figure 9, in that the electrode which is designated by the reference character da is solid and is surrounded by a tube @l of magnetic material. The insulated housing to is not shown in Figures 9 and 10. The operation of the two devices shown in Figures 9 and 10 is substantially the same as that described for the previous views oimy invention and it is to he pointed out that my invention works equally well regardless of whether the flux at the throat of the fountainlike path is concentrated as it would be in the device in Figure 9 or whether .the ux at theI throat is distributed in a circle as would be the oase withthe device shown in Figure 10.

The vdevice shown in Figure l1 is of substan- .tially the same construction as that shown in Figure 9 except that the plug which is inserted within the hollow electrode Se is made of a permarient magnet material and is designated -by the reference character i i. Also, the tubular body 3d may be constructed oi a permanent magnetic material and is therefore designated by the reference character ld. The device shown in Figure l2 is substantially the vsame as the device shown in Figure i0 except that the shell which surrounds the electrode Sii is made of a permanent magnetic material and is designated by the reference character l2. The outside shell l@ in Figure 12 is the same as that 'shown in Figure 11 and may comprise permanent magnetic material. In the two devices in Figures 1l and l2, both the central pole or lthe outside enclosure shell l@ may be made of permanent magnetic material, or only one may be made of permanent magnetic material with the other of non-permanent magnetic material, so long as suicient magnetic flux is set up to control the structure of the electrical discharge or' arc between the two interrupting electrodes. `1in the case of both the cone-shaped arcand the frustum of lthe cone-shaped arc, a standing arc discharge is drawn inwardly toward the central portion of the volume of space between the electrodes, the cone arc, however, being drawn inwardly further .than the frustum of' the cone arc. As the arc is drawn inwardly from along or looping uncontrolled arc it becomes shorter and shorter and the resistance of the arc becomes greater and greater,v regardless of whether the arc finally takes the form of a cone or nally takes .the form of the frustum of the cone. Under a strong magnetic eld, the glow appearance and the structure of the arc seems to be the same for both. the cone-shaped arc Vand the frustum of a cone-shaped arc. Also, in both cases of the coney shaped arc and the frustum of a cone-shaped arc,

the end of the arc line which plays on the movable electrode is forced inwardly with a greater yforce than the end of the arc line which plays on the stationary electrode. However, 1the coneshaped arc is forced inwardly towards the central portion of the electrodes with a greater force than the force which tends to force the lirustuin of a cone-shaped arc inwardly, and thus 4the interruption of the cone-shaped arc is clearly conned between the electrodes. The frustum oi the cone-shaped arc is caused to play upon the electrodes in the region of the marginal edge thereof where the ux lines are, the strongest and 'thus .the arc is extinguished very quickly.

With the interruption of alternating current by fa single-break contactor, as shown for example in Figure l, the arc tends to alternate between Ithe cone-shaped arc and the frustum oi the coneshaped arc as the alternating current reverses.

'When .the double-breaking device in Figure e is used for interrupting alternating current, the arc at one set of separating electrodes for any single instant is cone-shaped, while the arc at the other set of separating electrodes at the same instant is a frustum of a cone.

The circuit interruptor in Figure 4 is drawn from a practical working device and the size, the proportion of the parts and the spacing between the separated electrodes bear a xed ratio scale relation to actual devices. Each of the windings eid in the actual device has approximately 31/.2 turns the same as shown in the'drawings and these turns are sucient to produce the required eld strength to render my device highly eective in interrupting the now of the large currents. For large load currents, the held will be large, rendering the interruption capacity correspondingly great. For repeated intermittent operations, currents as high as one hundred or more amperes may be successfully interrupted for thousands of operations without perceptible impairment of the contacts.

In this application it is noted that the post 2d in Figures 4, 5v and 7 vdoes not carry the load current. However, the post 2li in these figures is electrically alive. Therefore, in this application and in the claims, the term electrode is to be interpreted to include the post or any other part which is electrically alive even though no current iiows therethrough.

By means of my magnetic circuit construction, the. magnetic field has a central region and an outer annular region with the magnetic ux field in the outer annular region stronger than the eld in the central region. The electrodes may beconsidered as having a central region and an outer annular region which may substantially register respectively with the central region and the outer annular region of the magnetic eld. The field inv the outer annular region is strong enough and reacts with the ux produced by the arc itself to constrain the arc substantially within the central region when the arc current ows in one direction and to constrain the arc substan- 13 tially within the outer annular region when the arc current ilows in the opposite direction. In any event, regardless of the direction of ow of current in the arc, the arc is magnetically forced toward the central region and is forced inwardly to at least substantially within the outer annular region. In 'the drawings the distance that the electrodes separate is shorter than the distance that the flux travels in passing from one pole means to the other in my magnetic circuit, although it is to be understood that this relationship may be varied and still come within the purview of my invention.

Although I have described my invention with a certain degree of particularity, it is understood that the present disclosure has been made by Way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

I claim as my invention:

1. In a current interrupting device having at stituting said ilrst magnetic pole and an outer element having a portion disposed laterally of the post-element and constituting said second magnetic pole, said nrst magnetic pole being disposed substantially in alignment with the contacts and being positioned on the side of said abutting surface of said stationary contact which is opposite from said movable contact, and insulating means having a chamber for housing the stationary contact, the post element and the outer element, said insulating means having an opening connecting the chamber to the outside thereof, said movable contact being movable in said opening, said chamber having an internal wall for supporting the said outer element.

4. In combination, a switch comprising an insulating housing having a chamber, said housing having a rst part and a second part connected together, said second part having a recess with an internal wall comprising a portion of said chamber, said second part also having an opening connecting the recess to the outside thereof, a

least a rst and a second interrupting contact movable relative to each other, said relative movement dening a line of motion, the improvement of apparatus for arresting and extinguishing an arm between the interrupting contacts, said apparatus comprising a shell-like metal housing having an annular rim, a post element projecting in the housing, means for mounting the first contact on the post element, said second contact being movable in the housing beyond the annular rim and engaging the rst contact, said post element and said housing comprising a magnetic circuit having opposite pole portions forming an air gap through which flux passes, said post element constituting one pole portion and said annular rim constituting the other pole portion, the separation of the electrodes occurring in said air gap within the housing whereby an arc between the separating contacts is controlled by said iiux, said opposite pole portions being so disposed with reference to each other that a line drawn therebetween is other than a vright angle with respect to saidv line of motion.

2. In a current interrupting device having at least a first and a second interrupting contact movable relative to each other, said relative movement defining a line of motionl the improvement of apparatus for arresting and extinguishing an arc `between the interrupting contacts, said apparatus comprising a post element and an annular member surrounding the post element, means for mounting the rst contact on the post element, said post element and said annular member comprising a magnetic circuit having opposite pole portions forming an air gap through which flux passes. said post element constituting one-pole portion and said annular member constituting the other pole portion, the separation of the contacts occurring in said air gap within the annular member whereby an arc between the separating contacts is controlled by said flux, said opposite pole portions being so disposed with reference to each other that a line drawn there between is other than a right angle with respect to said line of motion.

3. In combination, a switch comprising a stationary contact and a movable contact arranged to interrupt a circuit, said stationary contact leaving an abutting surface against which the movable contact engages, a magnetic circuit comprising first and second magnetic poles between which flux passes, said magnetic circuit including a post element having an end portion constationary contact and a movable contact arranged to interrupt a circuit in the chamber. said movable contact being movable in said opening. a magnetic circuit comprising rst and second magnetic poles between which ilux passes, raid magnetic circuit including a post element connected to the rst part of the housing and projecting into the recess and an outer element disposed laterally of the post `element and supported by the internal wall of the recess, said post element having an end portion -supporting the stationary contact in the recess and constituting said rst magnetic pole and said outer element having a substantially annular portion constituting said second magnetic pole.

5. In combination, a switch comprising an insulating housinglhaving a chamber, a stationary contact and a movable contact arranged to interrupt a circuit in the chamber, said chamber having an open end to receive the movable contact, said housing comprising an insulating support member and an insulating body member having an annular internal wall constituting a portion of the chamber, a first element composed of magnetic material mounted on the insulating support member and having a projection portion extending into said chamber toward the open end thereof, said projection portion supporting the stationary contact upon the end thereof and constituting a first magnetic pole, a second element composed of magnetic material disposed between the first element and the annular internal wall of the chamber and having a portion constituting a second pole, wall means in the chamber dening a surface having a rst portion, a second portion and a third portion, said portions in the order named comprising a series of surfaces extending from the stationary contact to the open end of the chamber in a region of the vicinity of the movable contact, said rst portion including the external surface of the first element, said third portion including the internal surface of the second element and said second portion comprising insulating material and being disposed intermediate the rst and third portions, said wall portions defining an annular recess having an open end communicating with the space surrounding the contacts in the vicinity of the arc, said rst and third wall portions deiining the said open end of the recess with the second wall portion disposed in the recess, and winding means surrounding the first element for passing flux between said poles, said ux substantially keeping the arc away on the other side thereof a from the said open end of the recess and protecting the second portion in the recess from the arc to prevent deposits created by the arc from entering said recess and lodging upon the second portion and establishing a conductive path between the iirst and third portions.

6. In combination, a switch comprising an insulating housing having a chamber, a stationary contact and a movable contact arranged to interrupt a circuit in the chamber, said chamber having an open end `to receive the movable contact, said housing comprising an insulating support member and an insulating body member having an annular internal wall constituting a portion of the chamber, a first element composed of magnetic material mounted on the insulating support member and having a projection portion extending into said chamber toward the open end thereof, said projection portion supporting the stationary contact upon the end thereof and constituting 'a first magnetic pole, a second element cornposed of magnetic material disposed between the rst element and the annular internal wall of the chamber and having a portion constituting a second pole, wall means in the chamber defining a surface including the external surface of one of said elements and having a first portion, a second portion and a third portion, said portions in the order named comprising a series of surfaces extending from the stationary contact to the open end oi the chamber in a region of the vicinity of the movable contact, said second portion comprising vinsulating material and being disposed intermediate the rst and third portions, said wall portions dening an annular recess having an open end communicating with the space surrounding the contacts in the vicinity of the arc, said rst and third wall portions defining the said open end of the recess with the second wall portion disposed in the recess, and winding means surrounding the first element for passing iiux between said poles, said iiux substantially 'keeping the arc away from the said open end of the recess and protecting the second portion in the recess from the arc to prevent deposits created by the arc from entering said recess and lodging upon the second portion and establishing a conductive path between the first and third portions.

7. in combination, a switch comprising a stationary contact and a movable contact arranged to interrupt a circuit, a housing having a large chamber with an enclosure wall for housing the contacts, a post element in housing supporting the stationary contact, said large chamber having on one side thereof a recess and having all chamber, said small chamber connecting large chamber to the outside of the housing and'coniprising an opening in which the movable contact operates, means for arresting the interrupting movements of said movable contact in said small chamber, said recess being deiined in part by said post element and said stationary contact and having an endless insulating surface which extends transversely across 'a path extending between said stationary contact and said opening in which the movable contact operates. and magnetic circuit means including said post element and a magnetizable winding surrounding the post element for substantially keeping the arc from said recess to preventdeoosits created by the arc from enteringsaid recess and lodging upon the endless insulating surface thereof.

8. In combination, a switch comprising a stav prising rst magnetic pole means and a second magnetic pole means between which iiux passes, said magnetic circuit including a post element having an end portion for supporting the stationary contact and an outer element disposed laterally of the post element and having an opening in which the movable contact operates, said end portion of said postelement including the iirst magnetic pole means and said outer element including the second magnetic pole means, said first magnetic pole means beingA disposed substantially in longitudinal' alignment with the contacts and being longitudinally spaced from the second magnetic pole means, whereby a line drawn between the magnetic pole means is at an angle other than a right angle'to the longitudinal axis of the post element. Y

9. In a circuit interrupter, a magnetic circuit having rst pole means and second pole means betweenv which flux passes, said first pole means including an elongated element having a longitudinal axis and having an end portion provided with an end surface constituting a rst pole face and said second pole means including substantially an annular member having an annular surface constituting a second pole face, said annular surface being longitudinally spaced from the said end surface, whereby a line drawn from said first pole face to said second pole face is other than a right angle with'respect to the longitudinaly axis of the elongated element, a stationary contact mounted on the end portion of the elongated element, and a movable contact adapted to engage the stationary contact, said second pole means being electrically insulated from the stationary contact means, said annular surface surrounding the movable contact in the closed circuit position and being so longitudinally spaced with respect to the stationary contact that said annular surface is intermediate said contacts in the open circuit' position.

i0. In combination, a switch comprising a stationary contact and a movable contact arranged to interrupt g circuit, a magnetic circuit means for producing a eld to extinguish an arc between the contacts, said magnetic circuit means coniprising centrai and outer members dening substantially coaxial pole pieces between which iiux passes, the separation of the contacts occurring between said pole pieces, said central pole piece supporting said stationary contact and being foreshortened with respect to the outer pole piece, whereby a line drawn between said pole pieces is other than a right angie with respect to the axis of the central pole piece.

combination, a `switch comprising an insulating housing having a chamber, a stationary contact and a movable contact arranged to vinterrupt a circuit in the chamber, said chamber having an open end to receive the movable contact, said housing comprising an insulating supchamber and having a portion constituting a second pole, wall means in the chamber dening a. recess including the external surface of one of said elements and the annular internal wall of the insulating body member, said recess extending from the stationary contact toward the insulating support; member, and winding means surrounding the first element for creating iiux between the poles.

12. A circuit interrupter comprising an insulating housing having a chamber with an annular internal wall, a post element of magnetic material supported by the housing and projecting into the chamber, cooperativecontacts to be engaged and disengaged in said chamber and comprising a stationary Contact member and a, movable con- Y tact member, said housing having an opening in of the housing through said opening in which the movable 'contact moves, magnetizable winding means mounted in the open recess and around the post element, and a member constituting a shell of magnetic material mounted in the recess and supported by the internal wall of the housing.

GERHaRD W. Prrrrxass.` 

